Microscopy Characterization (microscopy + characterization)

Distribution by Scientific Domains

Selected Abstracts

Atomic Force Microscopy Characterization and Interpretation of Thin-Film Poly(butylene adipate) Spherulites with Ring Bands

Andreas Frömsdorf
Abstract Atomic force microscopy characterization has been conducted to reveal the morphological difference between single-ring bands in poly(butylene adipate) (PBA). Furthermore, morphological features of the ring-less Maltese-cross spherulites are compared to the ring-band spherulites. Periodic changes in height seem to be common for either the ring-band or ring-less (Maltese-cross) crystal domains; however, the steepness in height change is greater for the ring-band crystal, while height change in the ring-less crystal exhibits a terrace-like layer pattern. In the ring-band crystal region, the lamellar stalks, which taper off to pointed needle-like stalks, monotonously protrude out of the layers of softer materials, with no signs of twisting, bending, or turning. In contrast, all lamellae in the ring-less (Maltese-cross) crystal region are uniform platelets arranged like flower petals in a layered pattern. [source]

Raman and transmission electron microscopy characterization of InN samples grown on GaN/Al2O3 by molecular beam epitaxy

J. Arvanitidis
Abstract Raman spectroscopy and transmission electron microscopy were employed to study the vibrational properties and the microstructure of epitaxially grown InN films on GaN/Al2O3 templates. The variations of the InN lattice constants, as deduced by electron diffraction analysis, along with the red-shifted E22 mode frequency reveal that InN films exhibit residual tensile stress, strongly dependent on the epilayer growth temperature. Threading dislocations are the dominant structural defects in the films, having a density in the order of 109,1010 cm,2. Profile analysis of the E22 Raman peak by means of the Spatial Correlation Model provides useful information concerning the effective mean length for free phonon propagation (L), which is a measure of the structural quality of the samples. In all the studied samples, L monotonically increases with decreasing threading dislocation density of pure screw and mixed type character. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Ternary miscibility in blends of three polymers with balanced binary interactions

E. M. Woo
This study demonstrates and discusses ternary miscibility in a three-polymer blend system based on balanced binary interactions. A truly miscible ternary blend comprising poly(,-caprolactone) (PCL), poly(benzyl methacrylate) (PBzMA), and poly(vinyl methyl ether) (PVME), was discovered and reported. Miscibility with phase homogeneity (excluding the PCL crystalline domain) in a wide composition range has been demonstrated using criteria of thermal transition behavior, cloud point, and microscopy characterization. At ambient temperature, the three-polymer ternary system is completely miscible within the entire composition range (i.e., no immiscibility loop). However, at slightly elevated temperatures above the ambient. phase separation readily occurred in this originally miscible ternary blend. A quite low "lower critical solution temperature" (LCST) near 75°C was found for the ternary blend, which is much lower than any of those for the binary pairs. Balanced interactions with no offsetting ,, among the three binary pairs were a key factor leading to a ternary miscible system. [source]

Photoluminescent Properties of SrTiO3:Pr, Al Nanophosphors Synthesized by Microemulsion,Microwave Heating

Qi Pang
A novel approach for the preparation of SrTiO3:Pr, Al nanophosphors by microemulsion,microwave heating is reported in this paper. In comparison with the conventional solid-state sintering processes, this novel method provides a limited small space in a micelle for the formation of nanosized precursors and requires a very short heating time, thus reducing the energy consumption. As a result, small-sized particles with a narrow size distribution and high purity were produced. Transmission electron microscopy characterizations indicated that the synthesized particles were almost spherical with an averaging diameter of ,24 nm and agglomerates slightly. The X-ray diffraction analysis revealed the perovskite cubic structure of SrTiO3:Pr3+ nanoparticles. The luminescent of SrTiO3:Pr, Al phosphors were investigated by photoluminescence. Under 350 nm excitation, SrTiO3:Pr, Al showed a strong red emission, peaking at around 615 nm. The photoluminescence excitation intensity was enhanced by the addition of Al3+ ions. [source]